A gang of bicycle thieves is believed to be targeting patrons at the Australian Open, with reports that up to 10 bikes were stolen from outside the grand slam tournament in just one day last week.

Bicycle Victoria has issued a warning to cyclists after receiving numerous reports of robberies at Melbourne Park in the past few days.

Bicycle Victoria spokesman Garry Brennan said one man whose bike was stolen had returned to a bike rack at Melbourne Park to find five locks had been cut through and were lying on the ground.Advertisement: Story continues below

"Another cyclist said the police had told him that they'd had 10 reports [of bicycle thefts] on one day," Mr Brennan said.

"If it is 10 bikes then it has almost got to be an organised gang."

He said the thieves were believed to be using heavy-duty bolt cutters to destroy locks and cables used to secure the bicycles.

Most of the thefts were reported to Bicycle Victoria today, suggesting the gang began was operating in earnest over the weekend.

Bicycle Victoria has urged cyclists to use a sturdy lock to secure their bikes to a fixed object, such as a parking meter, or a dedicated bike rack.

Mr Brennan also warned cyclists to ensure the item they chained their bike to could not be moved.

"I rode down [to Melbourne Park] myself yesterday and had a look and I saw bikes chained up to temporary fences, to trees, all around the place," he said.

They should also be locked in a visible, well-lit location with other bicycles.

Another option was for cyclists to lock their bicycles in the city and ride a blue bike from Melbourne's new bike hire scheme to the tennis.

A Victoria Police spokeswoman said police had received eight reports of bicycles being stolen from Melbourne Park in the past week.